Control of an Acoustic Mode by a Digitally Created Nonlinear Electroacoustic Absorber at Low Excitation Levels: Experimental Results

In this study, an acoustic mode of a tube is controlled by a digitally created nonlinear electroacoustic absorber (NEA) at low excitation levels, where the nonlinearity cannot be normally activated in passive vibro-acoustic absorbers. A comparison is carried out between a linear electroacoustic absorber, similar to a tuned mass damper (TMD) in mechanics, and a digital NEA. The innovative method for creating a NEA lies on real-time integration of the dynamics of the device. It permits to choose any behavior of the system by digitally programming the corresponding targeted dynamics. Here, a loudspeaker impedance control law with a cubic stiffness is considered, as this system is well-known in mechanics and provides nonlinear phenomena that are highlighted at low and moderate excitation levels in our study.